Partly regret spitting over better advisor (7)
I believe the answer is:
tipster
'better advisor' is the definition.
'tipster' can be an answer for 'advisor' (tipster is a kind of advisor). I'm unsure of the 'better' bit.
'partly regret spitting over' is the wordplay.
'partly' indicates the answer is hidden within the clue.
'over' says the letters should be written backwards.
'retspit' is hidden within 'regret spitting'.
'retspit' written backwards gives 'TIPSTER'.
Can you help me to learn more?
(Other definitions for tipster that I've seen before include "Racing tout" , "Supposed expert on horses" , "Person who points out likely race winners" , "I have a horse" , "One predicting winners" .)